influence of applied mineralogy in developing an optimal hydrometallurgical processing route for
Transcript of influence of applied mineralogy in developing an optimal hydrometallurgical processing route for
INFLUENCE OF APPLIED MINERALOGY
IN DEVELOPING AN OPTIMAL
HYDROMETALLURGICAL PROCESSING ROUTE
FOR COMPLEX SULPHIDE ORES
P. A. OLUBAMBI
School of Chemical and Metallurgical Engineering,University of Witwatersrand, Johannesburg,South Africa, and Department of Metallurgicaland Materials Engineering, Federal University ofTechnology, Akure, Nigeria
S. NDLOVUJ. H. POTGIETER
School of Chemical and Metallurgical Engineering,University of Witwatersrand, Johannesburg,South Africa
J. O. BORODE
Department of Metallurgical and Materials Engineering,Federal University of Technology, Akure, Nigeria
The selection of an optimum technical and economic processing and
extraction route for minerals and metals requires complete knowl-
edge of the ore, especially its chemical and mineralogical composi-
tions, relative amounts, and grain size distribution. Thus, to obtain
optimum results during base metals recovery from complex sulphide
ore, processing must start from a sound and complete mineralogical
study. This work therefore investigates the influence of applied
Address correspondence to P. A. Olubambi, School of Chemical and Metallurgical
Engineering, University of Witwatersrand, Private Bag 3, Wits, Johannesburg 2050,
South Africa. E-mail: [email protected] or [email protected]
Mineral Processing & Extractive Metall. Rev., 27: 143–158, 2006
Copyright Q Taylor & Francis Group, LLC
ISSN: 0882-7508 print=1547–7401 online
DOI: 10.1080/08827500600563350
mineralogy in the selection of the optimal route for processing and
extracting base metals from complex sulphides, by studying the size,
mineralogy, and elemental distribution of Ishiagu bulk complex sul-
phide ore. Bulk complex sulphide ore from Ishiagu, in Eboyin State,
in the southeastern part of Nigeria, was sequentially crushed in a jaw
crusher and a cone crusher, and ground in a rod mill. The results
obtained during laboratory sieve analysis were used to evaluate its
size distribution. Identification of mineral phases distributed within
the sizes was determined by microscopy, using a scanning electron
microscope coupled with energy dispersed x-ray analyzer to produce
backscattered images. The elemental distribution was determined
by the optical emission spectrometry using x-ray fluorescence and
inductively coupled plasma-optical emission spectrometer. Results
obtained showed variations in elemental and mineralogical compo-
sition within the different sizes. The concentrations of zinc, copper,
and iron reduce as particle size decreases, while silicon, sulphur, and
lead contents increase. The overall results obtained were used as a
basis for predicting parameters for which optimal hydrometallurgical
recovery of the constituent’s metals could be achieved.
Keywords: complex sulphide ores, applied mineralogy, minerals
processing, base metal extraction
Complex sulphide ores are extremely complicated mineralogical associa-
tions, basically of chalcopyrite, galena, and sphalerite finely disseminated
in a matrix of pyrite (Gomez et al. 1997), usually composed from the
minerals pyrite (FeS2) and arsenopyrite (FeAsS2). They are generally
made up of fine intergrown minerals, in which precious metals such as
gold and silver often occur as interlocked refractory and finely dissemi-
nated metals in them. They usually occur as hydrothermal deposit; as
epigenetic—skarn and=or vein, and syngenetic—volcanic massive sul-
phide (VMS) or sedimentary massive sulphide (Sedex).
Whatever the form in which the different elements occur, they
usually are very difficult to process (Deveci et al. 2004; Rubio and Frutos
2002). This may be due to the close similarities in their mineralogical
properties, which hinders their suitability for conventional methods of
processing. Due to their poor electromagnetic properties, they are
unsuitable for the magnetic method of separation, while the closeness
in their specific gravities limits their suitability for the gravity concen-
tration and heavy medium separation methods. Moreover, the metal
values in the sulphide minerals are prevented from being chemically
144 P. A. OLUBAMBI ET AL.
modified by reagents during flotation and are hindered from chemical
attack during leaching. In the hydrometallurgical process for treating
and extracting metals from these ores, it is observed that sulphide ores
do not allow the recovery of metal by direct chemical leaching (Dutrizac
1989; Hiskey and Wadsworth 1975) because the sulphides are insoluble
in nearly all reagents. For the metal content to be leached either through
the chemical or even the bioprocess, the reagent=organism must come
into direct contact with metal atoms or metal-containing compounds
within the mineral ore.
An approach to achieving this is to thoroughly liberate all the min-
eral phases in order to enable them to be exposed to chemical attack.
A limitation to grinding many sulphide ores is that the ore cannot prac-
tically be ground down fine enough to expose the metals. For instance,
chalcopyrite and sphalerite are frequently intergrown, with micro-size
grains of 10–20 mm being dispersed within the pyrite (Gomez et al.
1999). Therefore, due to these specific mineralogical characteristics,
it is necessary to finely grind and concentrate the ore prior to the solu-
bilization of the valuable metals (Barbery et al. 1980). However, the
crushing and grinding of ore is a significant capital and operational cost
in many mineral-processing plants. According to Bilgili and Scarlett
(2005), size reduction is an expensive and energy-inefficient process,
however operated. Considering these factors, a small gain in commi-
nution efficiency can have a large impact on the operating cost of a plant,
while conserving resources as well (Fuerstenau et al. 1999). Hence, it is
important to fully determine the comminution parameters that are
relevant to the crushing and milling of an ore to enable complete plant
design to take place.
The increase in the complexity during the processing of complex sul-
phide ore and their cost implications has put a formidable challenge to
the process engineer in designing suitable recovering routes and the
operation of metallurgical plants. These complexities therefore necessi-
tate a detailed mineralogical characterization of such ores in determining
an optimal processing route for its constituent minerals and metals.
Detailed mineralogical analysis plays an important role in overcoming
incorrect assumptions that may have disastrous consequences during
process design. Mineralogical characterization provides a sound back-
ground in understanding the behavior of the minerals during beneficia-
tion and the designing of optimal beneficiation routes. It also provides
insights and information on the type, nature, and amount of minerals
MINERALOGY FOR PROCESSING COMPLEX SULPHIDE ORES 145
and elements present within the ore, and the mineralogical reason(s)
governing the metal-recovery processes.
This process of applying mineralogical information to understanding
and solving problems encountered during the processing of ores and
concentrates is referred to as applied mineralogy (Petruk 2000). It
involves characterizing minerals and interpreting the data with respect
to mineral processing (Xiao and Laplane 2004). This data guides the
process engineer in the determination of the optimal processing and
extraction route. This article therefore studies the size and the mineral-
ogical and elemental distribution of Ishiagu bulk complex sulphide ore
and interprets the mineralogical data to predict parameters for which
optimal hydrometallurgical recoveries of base metals could be obtained
from the ore.
MATERIALS AND METHODS
Complex sulphide ore obtained from Ishiagu in Ebonyin state, Nigeria,
was used for this study. Morphological and qualitative analyses of the
bulk ore were performed using scanning electron microscopy (SEM)
equipped with energy dispersive X-ray (EDX) spectrum (SEM-EDX
technique). The ore was stage crushed in the laboratory in a jaw crusher
and later by a cone crusher. Ore grinding was carried out in a rod mill at
varying rod mill parameters. Ten rods of 460 g each were used for the
grinding. The grinding time and the amount of feed ore varied, as shown
in Table 1. Size analysis of the ground products from each of the varied
rod mill parameters were carried out to determine the quality of each
grinding parameter using the sieve analysis method in a laboratory test
sieve. After the sieve analysis for the different milling routes, the same
Table 1. Sizes reduction processes
Milling route
Milling parameters
No. of rods Amounts of ore (g) Time (s)
A 10 1000 5
B 10 1000 10
C 10 1000 15
D 10 2000 15
E 10 500 15
146 P. A. OLUBAMBI ET AL.
amount of ore samples of the size fractions from each of the grinding
routes were mixed together. Ten grams each of the homogenized parti-
cles of sizes of �53, 53, 75, and 106 mm, were mixed together, further
ground to a powder, and 2 g of the homogenized sample was subjected
to elemental analysis to give the composition of the bulk ore total. Identi-
fication of mineral distribution within the sizes was determined by x-ray
diffractometry using Philips PW 1830 x-ray diffractometer with a
Cu-anode. Mineral liberation pattern within the sizes was determined
using the SEM model JEOL 840, combined with EDX analysis to pro-
duce backscattered images (BSI). Quantitative analysis of the elemental
distribution was determined by x-ray fluorescence with Magi 00X Pro
XRF spectrometer at 4 KV, using IQþ ‘‘Standard less’’ analysis and
optical emission spectrometry using the inductively coupled plasma—
optical emission spectrometer (ICP-OES) model SPECTRO CIRO.
RESULTS AND DISCUSSION
Mineral Phases, Morphology, and Liberation
Major mineral phases identified through the x-ray diffraction include sid-
erite, sphalerite, galena, quartz, and traces of chalcopyrite. The sphalerite
in the ore occurs as sphalerite ferrous while the chalcopyrite occurred
as a chalcopyrite group mineral with chemical formula Cu2MnSnS4.
Rietveld analysis indicates that the ore contains 42% siderite, 35%
sphalerite, 11% galena, and 8% quartz. The percentage composition
for the chalcopyrite group mineral could not be accurately determined
by the Rietveld analysis. This might be due to the fact that the relative
amount is less than 2% (Kile and Eberl 2000).
Figure 1 shows different morphologies of the bulk complex ore
examined directly without polishing by SEM. The galena-rich phase
shows the characteristic galena cleavage and the box-shaped polyhedral
habit, with small grains. These grains with the characteristic cleavage
and crystal habit might have an effect on strength and could therefore
enhance easy breakage during comminution. The fine-grained massive
morphologies of the sphalerite-rich phases with flat surfaces and their
distinct crystallographic planes shown in Figure 1E and 1F also deter-
mine and indicate their flattened characteristics during breakage.
The mineral phases identified by SEM with EDX analysis through
BSI are as shown in Figure 2. The ore is typically made up of fine to
coarse grains intergrowths of the constituent crystalline phases both at
MINERALOGY FOR PROCESSING COMPLEX SULPHIDE ORES 147
the interstitials and the boundaries. Although there are several inter-
growths among the mineral phases, the fine to coarse structure of the
phases is expected to ease the liberation of the constituent mineral
phases. The major mineral phases are constituted essentially by siderite,
sphalerite, galena, quartz, and chalcopyrite group minerals. Other miner-
als occur as trace minerals and were not discriminated by image analysis,
similar to the analysis by Kahn et al. (2002). The mineral liberation
characteristics of the ore, as shown in Figure 3, revealed that the
liberation of the minerals is good. Although the ore showed mineral
intergrown nature, it could be understood that the intergrowths are less
Figure 1. SEM micrographs of the bulk ore showing different mineral morphologies. (A)
growth morphology of siderite; (B and C) growth morphologies of complex phases of
galena and quartz grains; (D) galena-rich phase with its characteristic cleavage and
box-shaped polyhedral habit, with some small grains; (E and F) fine-grained massive
morphologies of the sphalerite-rich phases with flat surfaces and their distinct crystallo-
graphic planes.
148 P. A. OLUBAMBI ET AL.
complex and the grain boundaries have little interpenetrations. The lib-
eration might also have been promoted by the differences and combi-
nation of both transgranular and intergranular fracturing liberation,
which might cause grains to be released easily.
Size-Reduction Characteristics
The effectiveness of practically all mineral processing and extraction
processes is a function of the size of the particle treated. Because of
the comparatively high cost of size reduction (Benzer 2005) and the
difficulties associated with separating minerals when over- or under-
liberation occurs, it is essential that the correct amount of size reduction
Figure 2. SEM=BSI micrographs of the bulk ore after polishing, showing the morphologies
and fine-to-coarse grains intergrowths of the constituent crystalline phases; sphalerite
(sph), galena (gal), siderite (sid), and quartz (qrt). (A) Intergrowths of chalcopyrite group
mineral (lighter gray) with sphalerite (light gray), and the intergrown of quartz (black) with
siderite (dark gray); (B) very complex intergrowth nature of the ore with grain boundaries of
sphalerite, galena (white), and quartz intergrown together with siderite; (C) fine-grained
and complex intergrowths of siderite, sphalerite, and galena; (D) fine intergrowths at the
interstitials and boundaries of sphalerite and quartz.
MINERALOGY FOR PROCESSING COMPLEX SULPHIDE ORES 149
be achieved. To this end, size analysis was carried out on the products of
all the rod mill parameters (amount of feed, no amount of rod and
milling time) varied to determine the optimal size reduction (grinding)
process. The results of the size analysis, as presented in Figure 4A and
4B, show that, at longer grinding times, more particles of lower particle
sizes were obtained. This implies that grinding time has a positive effect
on size reduction. It was also observed that the amount of feed ore has a
negative affect on size reduction of the ore, as revealed by more particles
of a larger size at higher amounts of feed ore. Results also show that the
particles were mostly distributed in the size range of þ106 mm–150 mm,
with the exception of grinding 500 g at 15 min. These observations there-
fore present options for which the selection of rod mill parameters for
grinding the ore could be easily estimated to obtain any desired particle
size and to reduce excessive grinding. There also was a general change in
the linearity of the particle breakage in all the milling routes. These
might be attributed to changes in the heterogeneity of the particles being
ground, which could be due to conditions in which the larger particles
are ground preferentially or the larger particles become protected after
time (Fuerstenau et al. 2003).
Figure 3. SEM=BSI micrographs of particle sizes of 106, 75, 53, and �53mm showing the
mineral Liberation pattern.
150 P. A. OLUBAMBI ET AL.
Figure 4. (A) cummulative weight retained (%) against particle size (mm) and (B) gate
Gaudin–Schuhmann size distribution of the grinding routes.
MINERALOGY FOR PROCESSING COMPLEX SULPHIDE ORES 151
Particle-size analysis is of great importance in the design of an opti-
mal process for mineral processing and extraction, and several studies
have been carried out to determine its effects on mineral recovery
(Deveci 2004; Hossain et al. 2004; Ozcan et al. 2000). It is observed,
however, that particle size alone may not reveal enough information
about a process to allow process optimization (Barrett 2003). Although
particle size analysis provides information on measuring the extent of the
liberation of the value minerals from the gangue at various particle sizes
and determines the optimum size of feed to the process for maximum
efficiency as well as the size range at which any losses are occurring in
the plant so that they may be reduced, it does not provide detailed infor-
mation on the distribution of the constituent minerals and elements
within the various size ranges to ascertain the degree of the reduction
of specified minerals. While they are useful for characterizing and
determining efficiency, they offer little information about the breakage
characteristics of the material within the comminution system (Fuerstenau
et al. 1999).
Elemental Distribution and Quantitative Analysis
In order to fully understand minerals’ behavior during comminution
from mineralogical point of view, minerals and elemental distribution
among five different particles sizes were analyzed. Mineral identification
(Figure 3) was also carried out, which were similar to those by Zapata-
Massot et al. (2004) in which SEM was used to acquire images of the
particles and particles in various families were classified. Table 2 show
the XRF and ICP-OES results for the distribution of elements within
Table 2. Percentage composition and distribution of the elements
Sample
X-ray fluorescence
spectroscopy (XRF)
Optical emission
spectrometry (ICP-OES)
O Zn Fe S Pb Si Mn Cu Mg Ca Al Cd
Bulk ore total 31.33 25.53 12.59 13.82 9.78 4.79 0.94 0.45 0.48 0.37 0.27 0.091
Size 106mm 33.33 26.63 11.98 13.55 9.02 3.02 0.89 0.52 0.44 0.34 0.15 0.099
Size 75mm 32.71 25.81 12.23 13.67 9.45 3.10 0.90 0.47 0.45 0.35 0.22 0.091
Size 53mm 32.61 25.05 12.96 13.91 10.15 4.23 0.91 0.42 0.52 0.37 0.28 0.088
Size �53mm 33.01 24.51 13.11 14.03 10.41 5.51 0.97 0.39 0.53 0.38 0.39 0.088
152 P. A. OLUBAMBI ET AL.
the sizes. The amounts of zinc, copper, and cadmium are reduced as the
particle size decreases while lead, iron, sulphur, and silica concentrations
increase.
From the results, it can be deduced that minerals’ response to break-
ing is largely determined by their mineralogical properties. It is largely
determined by the Bond work index (Casali et al. 2001) and its concept
has been used to evaluate the efficiency of a grinding circuit (Rowland
1973). It is a function of a mineral’s hardness, tenacity, cleavage, parting,
and fracture. These are in turn dependent on the atomic structure of that
mineral, which is controlled by the type of bonding and the distance
between the atoms. Cleavage takes place parallel to atomic planes where
the bonding in the crystal is weak, while parting results when minerals
break along planes of structural weakness. Though fracture is controlled
by crystal structure, it is an unpredictable form of breaking of a mineral
that does not follow a crystallographic direction and occurs because
there is equal bonding in all directions.
Sphalerite has a dodecahedral cleavage but fractures on uneven flat
surfaces; hence, during grinding, sphalerite fractures only along the flat
surface, resulting in flat particles that pose difficulties in reduction even
at higher grinding. Galena has a good cleavage and fracture, and there-
fore easily breaks along its cleavages, into cubes. This ability to break
along its cleavages with its soft and brittle properties makes its size-
reduction easy. The increase in silicon content at particles of lower sizes
could be traced to the mineralogical properties of quartz. Quartz is hard
and very brittle, and therefore breaks easily into fine particles due to its
good fracture, even though it has no cleavage. An increase in the amount
of sulphur at lower particle sizes could be attributed to the increase in
the degree of deformation, which caused some structural changes and
transformations. This was also observed by Hu et al. (2004), where great-
er amount of new lattice defects were produced on the surface of
mechanically activated pyrite because of the formation of elemental
sulphur during mechanical activation and the extremely incomplete
and cleavages.
Predictions for Process Selection and Design
The mineralogical differences among the constituent’s minerals within
the different sizes contribute to variation in their recoveries. This was
observed by Harbort et al. (1999), who found that a higher degree of
MINERALOGY FOR PROCESSING COMPLEX SULPHIDE ORES 153
grinding influenced to a greater extent the recovery of galena and
increased the rejection of sphalerite and pyrites. The size analysis of
the products from the five grinding routes gave clear information on
determining the choice of rod milling parameters for obtaining a speci-
fied particle size.
Figure 5 presents variable choices that a mineral processor can make
in deciding the process for obtaining a particular amount of size(s), while
the elemental distribution analysis shown in Table 2 determines relative
amounts of a particular element(s) within the size(s). Higher amounts of
particle sizes of �53, 53 and þ75 mm could be obtained through Process
E, while Process B gave the highest amounts of particles in the size range
of þ 106 mm. The elemental distribution (Table 2) gives the mineralogi-
cal basis for the recovery at any given particle size and is useful in ascer-
taining the relative recovery of specified metal. Acar et al. (2005)
adopted this principle and used the assays for respective size fractions
to calculate the quantitative data, which was compared with the bulk
sample (composite) assay. The type and amount of mineral present in
an ore determines the reactivity and recovery process, especially during
hydrometallurgical processing, and therefore governs the overall design
Figure 5. Weight retained (g) against particle size (mm).
154 P. A. OLUBAMBI ET AL.
process. For example, many sulfide minerals, including pyrite and
marcasite (FeS), pyrrhotite (Fe1�xS), chalcopyrite (CuFeS), and enargite
(CuAsS), generate acid when they interact with oxygenated water, while
other sulfide minerals, such as sphalerite (ZnS) and galena (PbS),
generally do not produce acid when oxygen is the oxidant (Plumlee
and Nash 1995).
The data in Table 2 can be used to determine the relative percen-
tages of metal recovered at a given particle size. Since there is variation
in the amounts of each element within the particle sizes, estimation of
percentage metal recovered would be a quotient of the percentage of
such metal within a particular particle size. The effects of associated
metal(s) within a particular particle size on the recovery of metal can
also be predicted at a glance. For instance, it is expected that the dissolu-
tions of copper and zinc are highest where the amount of iron is widely
distributed. This is due to the fact that the presence of iron has positive
effects on their recoveries (Rodriguez et al. 2003a, 2003b, 2003c).
According to Zielinski et al. (2000), this increase is believed to result
from the autocatalytic action of the dissolved iron rather than from the
distortion of the sphalerite lattice. Moreover, sulfide-rich mineral assem-
blages with high percentages of iron sulfide or sulfide minerals having
iron as a constituent (such as chalcopyrite or iron-rich sphalerite) will
generate significantly more acidic water than sphalerite- and galena-rich
assemblages that lack iron sulfide minerals (Plumlee and Nash 1995). On
the other hand, the presence of silica is expected to affect the dissolution
process, as it has been observed to cause a shift in iron mobilization
(Davis et al. 2001). High levels of silica alter the mineralogy of ferrous
oxidation products in natural systems, thereby leading to the precipi-
tation of more stable solid precipitate (Mayer and Jarrell 1996). Phoenix
et al. (2003) noted that iron may precipitate in the presence of silica as
either an amorphous Fe(OH)3(s) phase or as a poorly ordered hydrous
iron-silicate precipitates, e.g., ((Fe,Mn)SiO3,Fe23þSi2O7 � 2(H2O)) and
((Fe,Mg)3Si4O10(OH)2). The precipitate form therefore alters the reac-
tivity and redox behavior of ferrous ions. Rushing (2002) confirmed that
increased silica content decreases the rate of oxidation of Fe2þ to Fe3þ.
Moreover, silica has negative effects on solution purification process,
especially during the roast–leach–electrowining zinc extraction process
(DiFeo et al. 2001). In this case, such concentrates should be pretreated
to eliminate or reduce the silica content. In achieving this, additional
treatment and process cost is incurred (Lewis and Streets 1978).
MINERALOGY FOR PROCESSING COMPLEX SULPHIDE ORES 155
CONCLUSION
This study has clearly shown the role played by applied mineralogy in
determining an optimal hydrometallurgical recovery process for base
metals from complex sulphide ores. It also showed that the choice of a
grinding process is largely determined by the mineralogical properties
of the ore. The results obtained for the minerals and elemental dis-
tribution among the various particle sizes gave clear information on
which mineral process an engineer could base his choice of processing
route. In conclusion, when critical decisions are being made on recovery
processes, attention should not be solely based on particle sizes, but
more on the distribution of the constituent minerals and elements within
the sizes.
REFERENCES
Acar, S., Brierley, J. A., and Wan, R. Y., 2005, ‘‘Conditions for bioleaching a
covellite-bearing ore.’’ Hydrometallurgy, 77, pp. 239–246.
Barbery, G., Fletcher, A. W., Chem, C., and Sirois, L. L. 1980, ‘‘Exploitation of
complex sulphide deposit: A review of processing options from ore to
metal.’’ In Conference, Roma, Italy: The Institution of Mining and
Metallurgy. p. 135.
Barrett, P., 2003, Selecting in-process particle size analyzers. Available at http://
www.cepmagazine.org/pdf/080326.pdf.
Benzer, H., 2005, ‘‘Modeling and simulation of a fully air swept ball mill in a raw
material grinding circuit.’’ Powder Technology, 150, pp. 145–154.
Bilgili, E. and Scarlett, B., 2005, ‘‘Population balance modeling of non-linear
effects in milling processes.’’ Powder Technology, 150, pp. 59–71.
Casali, A., Gonzalez, G., Vallebuona, G., Perez, C., and Vargas, R., 2001,
‘‘Grindability soft-sensors based on lithological composition and on-line
measurements.’’ Minerals Engineering, 14(7), pp. 689–700.
Davis, C. C., Knocke, W. R., and Edward, M., 2001, ‘‘Implications of aqueous
silica sorption to iron hydroxide: Mobilization of iron colloids and inter-
ference with sorption of arsenate and humic substances.’’ Environmental
Science and Technology, 35, pp. 3158–3162.
Deveci, H., 2004, ‘‘Effect of particle size and shape of solids on the viability of
acidophilic bacteria during mixing in stirred tank reactors.’’ Hydrometal-
lurgy, 71, pp. 385–396.
Deveci, H., Akcil, A., and Alp, I., 2004, ‘‘Bioleaching of complex zinc sulphides
using mesophilic and thermophilic bacteria: Comparative importance of pH
and iron.’’ Hydrometallurgy, 73, pp. 293–303.
156 P. A. OLUBAMBI ET AL.
DiFeo, A., Finch, J. A., and Xu, Z., 2001, ‘‘Sphalerite–silica interactions: Effect
of pH and calcium ions.’’ International Journal of Mineral Processing, 61(1),
pp. 57–71.
Dutrizac, J. E., 1989, ‘‘Elemental sulphur formation during the ferric
sulphate leaching of chalcopyrite.’’ Canadian Metallurgy Quarterly, 28(4),
pp. 337–344.
Fuerstenau, D. W., Kapur, P. C., and De, A., 2003, ‘‘Modeling breakage kinetics
in various dry comminution systems.’’ KONA, 21, pp. 121–132.
Fuerstenau, D. W., Lutch, J. J., and De, A., 1999, ‘‘The effect of ball size on the
energy efficiency of hybrid high-pressure roll mill=ball mill grinding.’’
Powder Technology, 105, pp. 199–204.
Gomez, C., Blazquez, M. L., and Ballester, A., 1999, ‘‘Bioleaching of a Spanish
complex sulphide ore bulk concentrate.’’ Minerals Engineering, 12(1),
pp. 93–106.
Gomez, C., Limpo, J. L., De Luis, A., Blazquez, M. L., Gonzalez, F., and
Ballester, A., 1997, ‘‘Hydrometallurgy of bulk concentrates of Spanish
complex sulphides: Chemical and bacterial leaching.’’ Canadian Metallurgy
Quarterly, 26(1), pp. 15–23.
Harbort, G., Murphy, A., Vargas, A., and Young, M., 1999, ‘‘The introduction of
the IsaMill for ultrafine grinding in the Mt Isa Lead=Zinc concentrator.’’
Extemin99, Arequipa, Peru, September.
Hossain, S. M., Das, M., Begum, K. M. M. S., and Anantharaman, N., 2004,
‘‘Bioleaching of zinc sulphide (ZnS) ore using thiobacillus ferrooxidans.’’
Institution of Engineers (India) Chemical Division, 85, pp. 7–11.
Hiskey, J. B. and Wadsworth, M. E., 1975, ‘‘Galvanic conversion of chalco-
pyrite.’’ Metallurgical Transactions, 6B, pp. 183–190.
Hu, H., Chen, Q., Yin, Z., Zhang, P., and Wang, G., 2004, ‘‘Effect of grinding
atmosphere on the leaching of mechanically activated pyrite and sphalerite.’’
Hydrometallurgy, 72, pp. 79–86.
Kahn, H., Mano, E. S., and Tassinari, M., 2002, ‘‘Image analysis coupled with a
SEM-EDS applied to the characterization of a partially weathered Zn-Pb
ore.’’ Journal of Minerals & Characterization & Engineering, 1(1), pp. 1–9.
Kile, D. E. and Eberl, D. D., 2000, Quantitative mineralogy and particle-size dis-
tribution of bed sediments in the boulder creek watershed. Available at
www.brr.cr.usgs.gov=projects=SWC Boulder Watershed=WRIR Chapter7.
pdf.173–184.
Lewis, P. J. and Streets, C. G., 1978, ‘‘An analysis of base-metal smelter terms.’’
In Proceedings of the Eleventh Commonwealth Mining and Metallurgical
Congress, Hong Kong, pp. 753–767.
Mayer, T. D. and Jarrell, W. M., 1996, ‘‘Formation and stability of iron (II)
oxidation products under natural concentrations of dissolved silica.’’ Water
Research, 30(5), pp. 1208–1214.
MINERALOGY FOR PROCESSING COMPLEX SULPHIDE ORES 157
Ozcan, O., Ruhland, M., and Stahl, W., 2000, ‘‘The effect of pressure, particle
size and particle shape on the shear strength of very fine mineral filter
cakes.’’ International Journal of Mineral Processing, 59(2), pp. 185–193.
Petruk, W., 2000, Applied Mineralogy in the Mining Industry, Elsevier.
Phoenix, V. R., Konhauser, K. O., and Ferris, F. G., 2003, ‘‘Experimental study of
iron and silica immobilization by bacteria in mixed Fe-Si systems: implica-
tions for microbial silicification in hot springs1.’’ Canadian Journal of Earth
Science, 40, pp. 1669–1678.
Plumlee, G. and Nash, J. T., 1995, Geoenvironmental models of mineral deposits-
fundamentals and applications. Available at http://pubs.usgs.gov/of/1995/
ofr-95-0831/CHAP1.pdf.
Rodriguez, Y., Ballester, A., Blazquez, M. L., Gonzalez, F., and Munoz, J. A.,
2003a, ‘‘New information on the pyrite bioleaching mechanism at low and
high temperature.’’ Hydrometallurgy, 71, pp. 37–46.
Rodriguez, Y., Ballester, A., Blazquez, M. L., Gonzalez, F., and Munoz, J. A.,
2003b, ‘‘New information on the chalcopyrite bioleaching mechanism at
low and high temperature.’’ Hydrometallurgy, 71, pp. 47–56.
Rodriguez, Y., Ballester, A., Blazquez, M. L., Gonzalez, F., and Munoz, J. A.,
2003c, ‘‘New information on the sphalerite bioleaching mechanism at low
and high temperature.’’ Hydrometallurgy, 71, pp. 57–66.
Rowland, C., 1973, ‘‘Comparison of work indexes calculated from operation data
with those from laboratory test data.’’ In Proceedings of the X International
Symposium on Zeolites and Microporous Crystals, London, pp. 47–71.
Rubio, A. and Garcia Frutos, F. J., 2002, ‘‘Bioleaching capacity of an extremely
thermophilic culture for chalcopyrite materials.’’ Minerals Engineering, 15,
pp. 689–694.
Rushing, J. C., 2002, Advancing the understanding of water distribution system
corrosion: Effects of chlorine and aluminum on copper pitting, temperature
gradients on copper corrosion, and silica on iron release. M.S. Thesis
in Engineering. Faculty of the Virginia Polytechnic Institute and State
University, Blacksbury, VA.
Xiao, Z. and Laplante, A. R., 2004, ‘‘Characterizing and recovering the platinum
group minerals—A review.’’ Minerals Engineering, 17, pp. 961–979.
Zapata-Massot, C., Frances, C., and Bolay, N. L., 2004, ‘‘On the use of scanning
electron microscopy for the modeling of co-grinding kinetics in a tumbling
ball mill.’’ Powder Technology, 143–144, pp. 215–229.
Zielinski, P. A., Larson, K. A., and Stradling, A. W., 2000, ‘‘Preferential deport-
ment of low-iron sphalerite to lead concentrates.’’ Minerals Engineering,
13(4), pp. 357–363.
158 P. A. OLUBAMBI ET AL.